OBJECTIVE: To determine the roles of complex carbohydrates (glycoproteins and glycolipids) in germinal cell differentiation in the male testis. Glycoprotein metabolism Our main objective for the coming year will be to study the pattern of oligosaccharide branching of cell surface glycoproteins as germinal cells differentiate. We will also study the enzymes which effect this branching as cells differentiate. Glycolipid metabolism: We have discovered a novel glycolipid in mammalian testis called sulfatoxygalactosylacylalkylglycerol (SGG). We have been investigating the cellular and subcellular sites of synthesis of SGG and the fate of SGG during germinal cell differentiation. Our present model is as follows: SGG is sulfated in leptotene-zygotene primary spermatocytes within the Golgi apparatus. SGG quickly migrates to the cell surface and remains on the germinal cell surface with minimal (if any) turnover as the germinal cell differentiates from spermatocytes to spermatids to mature spermatozoa. Several aspects of this model remain to be firmly established. We are presently trying to use anti-SGG at the electron microscope level to pin down with more certainty the cellular and sub-cellular sites of SGG within rat testis. Also it is a paradox that spermatozoa are rich in SGG but SGG cannot be demonstrated on the spermatozoal cell surface with anti-SGG. We have evidence for a re-arrangement of SGG within the plasma membrane during differentiation and hope to explore this SGG mobility further with various physical and chemical (cross-linking) tools. Work is also in progress on the purification of the SGG sulfo-transferase, a Golgi-located enzyme, by affinity chromatography methods. If purified, antibody will be raised to this sulfotransferase to determine its cellular and subcellular location by immunocytochemical methods. It appears at present that this transferase is suddently turned on at the leptotene-zygotene stage and then just as suddenly turned off.